Erectable reflector construction

ABSTRACT

AN ERECTABLE REFLECTOR CONSTRUCTION HAVING A HUB WITH A PLURALITY OF MULTI-HINGED RADIAL ARMS ATTACHED AT THEIR ONE END TO THE HUB AND HAVING CORRESPONDING RIGID SEGMENTS BETWEEN WHICH EXTEND THIN FLEXIBLE REFLECTOR MEMBRANES. IN THE STORED STATE DURING TRANSPORT INTO SPACE, THE ARMS ARE FOLDED ACCORDIAN-LIKE THE HUB AND THE REFLECTOR MEMBRANES ARE ROLLED UP BETWEEN RESPECTIVE SECTIONS OF THE FOLDED ARMS. IN THE RELEASED STATE DURING ERECTION IN SPACE, TORSION SPRING MEANS ON THE ARM HINGES ACT AS MOTOR MEANS WHICH CAUSE THE ARM SECTIONS TO UNFOLD THE CONTINUOUS ALIGNED POSITIONS AND THE MEMBRANES TO UNFURL AND STRETCH TAUT INTO FLAT CONFIGURATIONS DISPOSED IN A COMMON PLANE.

' A ..G. BUCKINGHAM E A 'r Emagrmam REFLECTOR 'coNsTfiucMoN 5 Sheets-Sheet 1 Filed May 10,; 1957' ||||l III-IIIIIII-I llr'L-IL WITNESSES.

INVENTORS r Arthur G. Buckin h m 6 Frank C. Rushi v 197! A.G.BU CKINGHAM ETA!v 3,558,219

ERECTABLE REFLECTOR CONSTRUCTION med May 10; 19's? 1 3 Sheets-Sheet 2 FIG.3.

3,558,219 ERECTABLE REFLECTOR CONSTRUCTION Arthur G. Buckingham, Baltimore, and Frank C. Rushing, Ellicott City, Md., assignors to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed May 10, 1967, Ser. No. 637,419 Int. Cl. G02b /08 US. Cl. 350292 5 Claims ABSTRACT OF THE DISCLOSURE An erectable reflector construction having a hub with a plurality of multi-hinged radial arms attached at their one end to the hub and having corresponding rigid segments between which extend thin flexible reflector membranes. In the stored state during transport into space, the arms are folded accordian-like the hub and the reflector membranes are rolled up between respective sections of the folded arms. In the released state during erection in space, torsion spring means on the arm hinges act as motor means which cause the arm sections to unfold to continuous aligned positions and the membranes to unfurl and stretch taut into flat configurations disposed in a common plane.

BACKGROUND OF THE INVENTION Field of the invention.Collapsible-storage, erectable, reflector structure.

SUMMARY OF THE INVENTION An erectable reflector construction employing an unfurlable electromagnetic-wave-energy reflector means of thin flexible material connected to a multi-hinged unfoldable framework for the support and the multidirectional tensioning into a planar configuration, which framework is stabilized in its erected state by flexible guys anchored to an elongated central mast or boom.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 represents an exemplified embodiment of a space-erectable reflector construction in a fully-erected state;

FIGS. 2A and 2B are side and top views, respectively, of arm and reflector membrane portions of the structure in FIG. 1 in a collapsed state prior to erection;

FIG. 3 is a cross-sectional view of an exemplified construction of the hanged arms employed as rigid compression elements of a framework in the exemplified embodiment of the present invention;

FIGS. 4A, 4B and 4C are side, end and top views, respectively, of an exemplified construction of spring-biased hinges suitable for use with the FIG. 3 arm construction;

FIGS. 5A and 5B are top and side views, respectively, of an exemplified arrangement acting in behalf of defining stop positions for sections of the hinged arms shown in their unfolded extended positions;

FIGS. 6A and 6B are bottom and side views, respectively, of the FIG. 5 construction with the arms partially folded;

FIG. 7 is a plan view of the exemplified configuration of the reflector construction of the present invention in its fully erected state; and

FIG. 8 represents a multi-directional tensioning arrangement for the flexible reflector material.

United States Patent Olfice 3,558,219 Patented Jan. 26, 1971 DESCRIPTION OF THE PREFERRED EMBODIMENTS A schematic representation of the exemplified reflector construction 10 in its fully erected state is shown in FIGS. 1 and 7. A flat or planar reflector means 12 is defined by a number of reflector elements 14 of thin flexible material extending between and attached at opposite ends to a plurality of rigid radial spokes or arms 16 emanating from a central support member 18 or hub.

Referring to FIG. 7, the exemplified reflector construction is of generally circular shape and may be in the order of 500 ft. to 1000 ft. in diameter when employed, for example, to reflect solar energy onto the earth, and may have such as one-hundred eighty reflector elements 14 located in such as five concentric circular arrays about the central axis 20 of the reflector assemblage. Thirty-six radial arms 16 attached to the central mounting member 18 provide a framework for immediate support for the reflector elements 14. The length of each of these arms 16 may be in the order of 250 ft. to 500 ft. Support for the arms 16 to assure their alignment with respect to a common plane when in their extended erected configuration can be provided, at least in part, by a plurality of flexible tension elements in the form of guy wires 22 extending from opposite ends of a central mast or boom 24 passing through the central support member 18, which guy wires are attached at their opposite ends to opposite sides of the arms 16 at different radial locations therealong. Employment of such guy wires tends to relax the rigidity requirements imposed on the design of the radial arms.

In the erected state of the reflector construction in which it is shown in FIG. 1, the central boom 24 is rigid and free to float axialwise within the central mounting member 18. This arrangement permits movement of the arm and membrane assemblage as a whole in an axialwise direction around the boom 24 and prevents creation of restraining and distorting forces which otherwise could result from differential expansion of components at opposite sides of the reflector plane.

In use as a solar energy reflector for aiming sunlight at a selected area on a planet such as earth during orbit for a prolonged period of time, the reflector assemblage will undergo aiming movement which will introduce bending movements to the structure, solar pressure will exert an influence on the structure, thermal expansion will introduce stresses into the structure, acceleration torques will be introduced, and integrity of the flatness of the composite reflector surface will need be maintained in order to assure accurate aiming at the select earth site.

Referring to the several figures in the drawing, in accordance with an essential feature of the present invention, a reflector support framework is employed having a plurality of rigid compression elements 26 joined together by hinges. In the illustrative embodiments, these elements form parts of radial arms 16 with joining hinges 28 which are staggered alternately between the top and bottom locations of the arm sections to allow such arms initially to occupy the accordian-like folded position adjacent to the central arm support member 18, which folded position is shown in FIG. 2A and FIG. 2B. In such folded attitude of the arm sections or elements 26 the reflector elements or membranes 14 are in a collapsed rolled-up state disposed between adjacent corresponding arm sections to which opposite ends of such rolled-up membranes are attached by suitable means such as screwsecured bottom stripes 30, shown in FIG. 3. In assembly,

the membranes may be doubled over and then rolled from their doubled-over end as shown in FIG. 6A. During unfolding of the arms 16 as permitted by the hinges 28 such arms will be made to assume a straight position in which they are aligned longitudinally, and the reflector membranes or elements 14 will progressively unroll to assume a flat taut condition in the straight extended arm attitudes.

The reflector element or membrane 14 will be made of a relatively light, thin, flexible material, a fraction of a mil thick, for example, such as plastic materials sold under the trade name Mylar, Kapton, to which is vapor deposited, for example, a coating of such as aluminum.

To provide for unfolding of arms 16 during erection of the reflector construction in space, each of the hinges 28 is provided with a motor means, which may be helical torsion spring means 34 for example as shown in FIGS. 4A, 4B and 4C which biases the arm sections 26 joined by such hinges to a straight-line attitude. For rigidity, the construction of the arm sections 26, shown schematically in most of the figures of the drawings as straight lines or thin rods, may take a form such as shown in FIG. 3 in which each arm section will comprise three equally spaced-apart longitudinal rods 36 laterally joined together at intervals along their length by cross braces 38, which also may be rod-shaped. The hinges 28 and the unfolding Spring 34 arrangement of FIGS. 4A, 4B and 4C are shown in conjunction with employment with such truss-type arm section construction.

In such exemplification, the hinges 28 will employ end plates 40 rigidly secured to the longitudinal rod members 36 of the adjacent arm sections 26 between which such hinge is disposed. A central member 42 projecting from one end plate projects between lugs 44 on the other end plate and a pin 46 projecting through aligned openings in the lugs and in the central member defines the axis of rotary movement of the two end plates 40 of each hinge 28.

The motor means is exemplified in the form of two helical torsion springs 34, as shown in FIGS. 4A, 4B and 4C, at opposite ends of the pin 46. One end of each spring 34 may be anchored to such pin and the other end anchored to the one end plate 40. The swivel pin 46 is secured against turning within the spaced-apart lugs 44 while the projecting portion 42 of the one end member 40 is free to turn about the outer surface of such pin. The spring 34 is preloaded torsionally so that it tends to urge the adjacent arm sections 26 at opposite sides of the hinge into a straight-line attitude and to oppose the reverse angular movement thereof during folding of the arm sections. An adjustable stop screw 50 extending through one end member 40 for abutment at its projecting end with the other end member 40 serves to define the straight-line stop positions between the two adjacent arm sections 26 served by a given hinge, 28. A latch means 51, affixed to the one member 40 and locatable with a recess in the other member 40, serves to lock the hinges 28, hence the arm sections, when fully unfolded.

Referring to FIGS. 5A, 5B, 6A and 6B, a means which provides controlled tensioning of the reflector elements 14 is illustrated. Such means takes the form of flexible tension elements or strips 52 of high strength material to which the edges of the reflector membranes 14 are secured in lieu of direct securement to the arms. The strips 52 extend in a common plane above and along the arms 16 to tension springs 54 anchored to the outermost section 26 of each arm 16 to exert a limited pulling force on such strips and the elements 14 secured thereto when the arms are fully unfolded. In the partially folded state as shown partially in FIGS. 6A and 6B the strip 52 will be made to fold along the arm sections 26 in a relaxed state due to the shortened length of such arms which exist in a folded attitude.

It may be desirable to provide flexible cables 56, as shown in FIGS. 2A and 5B attached to arms 16 which are stored on a reel means (not shown) during the collapsed stowed condition of the reflector construction and which by unreeling during unfolding of the arms 16 impose a damping influence on such arms during their becoming unfolded such as by the spring means 34 at the arm section hinges 28 to assure that such unfolding will be smooth and continuous under the influence of such springs which will be of relatively high strength in behalf of assuring unfolding of the arms and unfurling of the reflector membrane. The damping means (not shown) may be such as a friction clutch afiiliated with the reels (not shown) from which such damping cables unwind during erection. Other forms of motor means, such as electric motor means which can be started, stopped, and/ or speed controlled may obviate any need for such damping means.

In regard to damping via cables, the guy wires 22 of FIG. 1 also will unreel during erection of the reflector structure and also may be provided with a damping means affiliated with the cable reels (not shown) of any suitable form.

Referring to FIG. 8, in order to assure that the thinfilm reflector elements 14 unfurl to a precisely flat configuration during unfolding of the arms 16, side edges of the thin-film elements 14 are shown attached to cables 60 anchored at opposite ends to the respective elements 16 of adjacent arms or to the flexible strips 52, as the case may be. During unfolding of the arms, the cables 60 will tend to stretch taut to exert an oppositelydirected pulling force on such elements transversely to the pull exerted thereon by such strips and/or arms.

We claim as our invention:

1. An erectable reflector construction comprising,

(a) a central support member (18),

(b) a plurality of radial arms pivotally connected at their inner end to said central support member (18) at circumferentially distributed locations therearound,

said radial arms each being composed of a plurality of rigid longitudinal elements (26) joined by hinges (28) permitting accordian-like folding of such arms radially inward into a compact state for storage and transport into space and unfolding radially outward to extended positions outwardly from said central support member,

(0) arm angulation-determining means (22, 24 in FIG. 1 and/or 40, 50 in FIG. 4A) for defining the angular attitude of the unfolded arms perpendicularly of their direction of outward extension,

(d) an electromagnetic wave energy reflector means (12) of thin flexible material connected to said arms said reflector means comprising a plurality of membranes (14) respective to the arm elements (26) so connected thereto as to permit rolled-up storage while such arms are folded and unrolling by such arms during their unfolding,

(e) and torsion spring means on said arms (16) at said hinges (28) to effect the aforesaid unfolding of such arms and unfurling of said reflector means.

2. The reflector construction of claim 1, wherein:

said arm angulation detremining means comprises a mast (24) extending from said central support member, and a plurality of guy wire means (22) extending from a remote location on said mast to longitudinal locations along said arms when unfolded.

3. The reflector construction of claim 2, wherein:

said mast (24) extends with radial freedom through said central support member (18) and said guy wire means (22) are distributed on both sides of the outwardly-extending array of unfolded arms (16).

5 4. The reflector construction of claim 1, wherein: References Cited said arm angulation determining means comprises stop UNITED STATES PATENTS 4 0 d th t t 'd E32: E 2 embo led m e cons Sal 2,534,710 12/1950 Golian et al. 343-91s 5. The reflector construction of claim 1, wherein: 3174397 3/1965 SanPm 350.292 said construction further comprises a plurality of 5 3,406,404 10/1968 Maler 350-289 flexible tension elements (52) yieldably connected by resilient means (54) to outer ends of the arms (16), DAVID RG, Pnmary Examiner and R. L. SHERMAN, Assistant Examiner said reflector means (12) is attached to said tension elements (52) and thereby connected to said arms. 10 

